Utra tdd time slots allocation

Abstract

This invention relates to an apparatus and method for allocating timeslots subscriber units in a time division duplex communication system ( 300 ). The communication system ( 300 ) has a number of frame synchronised base stations ( 301 ). The apparatus ( 301 ) comprises a switching point processor ( 323 ) which determines a switching point ( 223 ) between uplink and downlink timeslots in a time frame. It further comprises a power level processor 321 which determines power levels associated with communication from aplurality of subscriber units ( 307, 309, 311 ) to be allocated time slots. In addition the apparatus ( 301 ) comprises a time slots scheduler which allocates time slots in the time frame to the subscriber units ( 307, 309, 311 ) in response to the associated power levels. The invention is applicable to 3rd generation cellular communication systems such as the Time Division Duplex mode of UMTS.

1 . A method of allocating timeslots to subscriber units in a time division duplex communication system including at least a first and second substantially frame synchronised base station, the method comprising the steps of: 
 determining a switching point in a first time frame of the first base station between uplink and downlink timeslots;    determining power levels associated with communication from a plurality of subscriber units to be allocated time slots in the first time frame; and    allocating time slots of the first time frame to said plurality of subscriber units in response to said associated power levels by:    designating at least a first set of time slots close to the switching point;    determining a first power threshold; and    allocating time slots of subscriber units to said first set of time slots only if the associated power levels are below said first threshold value.    
   
   
       2 . A method of allocating time slots as claimed in  claim 1  wherein the time slots are allocated such that there is a concentration towards the switching point of time slots for subscriber units having relative lower associated power levels.  
   
   
       3 . (Cancelled)  
   
   
       4 . A method of allocating time slots as claimed in  claim 1  wherein the step of allocating time slots further comprises: 
 designating a second set of time slots close to the switching point;    determining a second power threshold;    and allocating time slots of subscriber units to said second set of time slots only if the associated power levels are below said second threshold value and above said first threshold value.    
   
   
       5 . A method of allocating time slots as claimed in  claim 1  wherein said first power threshold is determined in response to the associated power levels of the plurality of subscriber units.  
   
   
       6 . A method of allocating time slots as claimed in  claim 1  wherein said first set of time slots comprises a single time slot  
   
   
       7 . A method of allocating time slots as claimed in  claim 1  wherein said first set of time slots comprises a group of time slots adjacent to the switching point.  
   
   
       8 . A method of allocating time slots as claimed in  claim 1  wherein said first set of time slots is selected so as to include the time of a second switching point in a second time frame of the second base station.  
   
   
       9 . A method of allocating time slots as claimed in  claim 1  wherein time slots are allocated to subscriber units such that the associated power level increases with distance from the switching point.  
   
   
       10 . A method of allocating time slots as claimed in  claim 1  wherein said plurality of subscriber units includes all subscriber units requesting time slots  
   
   
       11 . An apparatus for allocating timeslots to subscriber units in a time division duplex communication system including at least a first and second substantially frame synchronised base stations, the apparatus comprising: 
 means for determining a switching point in a first time frame of the first base station between uplink and downlink timeslots;    means for determining power levels associated with communication from a plurality of subscriber units to be allocated time slots in the first time frame; and    means for allocating time slots of the first time frame to said plurality of subscriber units in response to said associated power levels comprising:    means for designating at least a first set of time slots close to the switching point;    means for determining a first power threshold; and    means for allocating time slots of subscriber units to said first set of time slots only if the associated power levels are below said first threshold value.    
   
   
       12 . An apparatus for allocating timeslots as claimed in  claim 11  wherein the means for allocating time slots is operable to allocate time slots such that there is a concentration towards the switching point of time slots for subscriber units having relative lower associated power levels.  
   
   
       13 . (Cancelled)  
   
   
       14 . An apparatus for allocating timeslots as claimed in  claim 11  wherein the means for allocating time slots further comprises: 
 means for designating a second set of time slots close to the switching point;    means for determining a second power threshold; and    means for allocating time slots of subscriber units to said second set of time slots only if the associated power levels are below said second threshold value and above said first threshold value.    
   
   
       15 . An apparatus for allocating timeslots as claimed in  claim 11  wherein the means for determining a first power threshold is operable to determine the first power threshold in response to the associated power levels of the plurality of subscriber units.  
   
   
       16 . An apparatus for allocating timeslots as claimed in  claim 11  wherein said first set of time slots comprises a single time slot  
   
   
       17 . An apparatus for allocating timeslots as claimed in  claim 11  wherein said first set of time slots comprises a group of time slots adjacent to the switching point.  
   
   
       18 . An apparatus for allocating timeslots as claimed in  claim 11  wherein the means for designating at least a first set of time slots is operable to select said first set of time slots so as to include the time of a second switching point in a second time frame of the second base station.  
   
   
       19 . An apparatus for allocating timeslots as claimed in  claim 11  wherein the means for allocating time slots time slots is operable to allocate subscriber units such that the associated power level increases with distance from the switching point.  
   
   
       20 . An apparatus for allocating timeslots as claimed in  claim 11  wherein said plurality of subscriber units includes all subscriber units requesting time slots